Lately, I noticed that my bathroom toilet developed a slow leak such that the water tank would refill by itself without anyone pushing the lever. I checked the flapper and noticed the flapper was well passed its usable life – lots of calcium deposit and the perimeter of the flapper developed rough surfaces to not seal properly with the outlet ring. See below:

I purchased a replacement Korky flapper with an adjustable air holes for adjusting the timing of the closing from 1 to 8.

I tried from 1 to 8 and flapper still closed too soon resulting in poor or weak flushes, which would eventually lead to build up and expensive rooting bills.

The one that did the trick, despite Korky’s video instructions, is to loosen slightly the chain that connects between the handle bar to the flapper. My guess is that the slack of the chain create a whiplash condition to float up the flapper momentarily and long enough for the flapper to stay up for more water to flow out. I noticed this particular trick in my previous blog here. If there is insufficient slack (too tight), the pulling force would cause the flapper to bounce off and close the flapper too fast. And if there is too much slack, the flapper would not open. You’d need to experiment to come up with a optimal slack. For me it’s around 3/4″ to 1″. There is a sweep spot in the amount of the slack. Play with it but conserve water if you’re in a drought situation like we do here in California.